The present invention relates to a method and apparatus for the protection of locks against forcible entry. The invention has particular application in the protection of security locks as found on, for example, safes against attack by drilling.
It is obviously important that locks and in particular lock mechanisms be protected against unauthorized access; such access attempts are often made by force. One field where locks must be secure against such attacks is in the area of self-service terminals (SSTs) used to deposit or dispense valuable media, particularly financial services centers (FSCs) and automated teller machines (ATMs); FSCs and ATMs are nearly always accessible to the public, and are known to contain large amounts of cash.
A conventional ATM contains a safe in which the banknotes to be dispensed by the ATM are stored. Access to the safe is gained through a door provided with a conventional safe lock, typically a combination lock. The lock mechanism is mounted on the inner face of the safe door and controls the release of a locking bar or bolt which secures the door.
At present, the lock is protected by the provision of what is known as a hard plate; that is, a plate of fully hardened steel mounted in an enclosure between the safe door and the lock mechanism. To open the safe door forcibly without damaging the valuable media within the safe it is necessary to drill through the safe door and the hard plate, typically at a number of locations, to gain access to the lock mechanism, which is then forced to release the locking bar or bolt. A conventional hard plate and a lock fitted with such a hard plate are shown in FIGS. 1 and 2 of the accompanying drawings.
Existing hard plates are capable of withstanding a drilling attack from carbide tipped drills for at least 10 minutes. However, drilling technology is constantly improving and recently developed solid carbide drills, although very brittle, are able to penetrate existing hard plates in a relatively short period.
A further problem with existing hard plates that has been identified by the applicants is that, once a hard plate is freed from its support on the lock spindle, which may be achieved by hammering the spindle into the safe, the hard plate may be pushed to the rear of the hard plate enclosure by the pressure of a drill. The plate comes to rest adjacent the internal lock mechanism, which provides a secure substrate for the drilling operation, and thus facilitates breach of the lock.
Provision of ever-harder and more drill-resistant hard plates is technically feasible. However, the cost of such materials would add disproportionally to the manufacturing costs of an ATM, the safe already being one of the most expensive single elements of a typical ATM.
It is among the objects of embodiments of the present invention to alleviate or obviate these and other problems of existing lock security features.
According to the present invention there is provided a secure container comprising:
an external wall including a door; and
a lock for securing the door, the lock comprising a lock mechanism located internally of the wall and a plate mounted between the wall and the lock mechanism, the plate being tiltable in response to applied pressure.
The invention also relates to a lock for fitting to such a secure container, and further to a hard plate for fitting to such a lock.
In use, the plate will tilt or move in response to applied pressure, away from the point of application. Thus, the plate will move to evade the point of a drill on the application of drilling pressure, such that the cutting point of the drill will have difficulty gaining or be unable to gain adequate purchase to begin cutting through the plate. The tilting of the plate will also result in the drill being subject to lateral forces; the hardest drills, such as solid carbide drills, are very brittle and are likely to break if an attempt is made to drill into a hard surface that is at an angle other than perpendicular to the drill axis.
Preferably, the material from which the plate is made is itself resistive to cutting by a drill, to provide additional security. Materials known in the art may be used, such as fully toughened steel. Alternatively, or additionally, the plate may be coated with a cutting resistant material.
Preferably, the plate is mounted on a pivot, conveniently at or adjacent the center of the plate. The pivot is conveniently provided by a tapered bush mounted on or around a lock spindle, which spindle extends from the internal locking mechanism to the exterior of the lock.
Preferably, the plate has a convex outer surface. Such a surface will tend to deflect a drill point and increase the likelihood of brittle drills snapping.
Preferably also, the plate is tiltable such that at least a part of the plate outer surface is at an angle of at least 31xc2x0 from the plane of the adjacent container wall. Standard metal drills have a point angle of at least 118xc2x0 (for drilling relatively hard metals the point angle tends to be higher), such that a drill extending through a hole drilled perpendicular to the container wall will cause the plate to tilt to an angle at which the drill point will be unable to achieve a point contact with the plate and thus will be unable to initiate the drilling of a hole in the plate.
Preferably, the plate is rotatable, most preferably through 360xc2x0. This is most conveniently achieved by mounting a circular hard plate in a corresponding circular lock housing. This construction provides an additional degree of freedom of movement for the plate, increasing the difficulty in stabilizing the plate to facilitate drilling and prevent breakage of brittle drills.
Preferably, the container is a safe, which may be incorporated in an automated teller machine (ATM).
According to a further aspect of the present invention, there is provided a method of protecting a lock mechanism provided in a secure container, the method comprising providing a tiltable plate between the lock mechanism and an external wall of the container.
According to another aspect of the present invention there is provided a secure container comprising:
an external wall including a door;
a lock for securing the door, the lock comprising a lock mechanism located internally of the wall and a plate mounted between the wall and the lock mechanism, the plate having an external surface which is inclined relative to the wall.
The plate surface may be inclined, conical, frusto-conical, concave or convex, or otherwise configured such that a drill located in a drilled hole in the container wall which is perpendicular to the wall will contact the plate surface at an angle other than 90xc2x0, and preferably at an angle such that the drill point will not contact with the plate surface, such that the drill point is unable to initiate drilling of a hole in the plate.